ABCG2 and neoplasm: Tumours derived from HOXB9 knockdown ALDH+CD44+CXCR4+CD24+ cells exhibited significantly decreased expression of hypoxia tolerance-related genes (APLN, HIF-1α), DNA damage repair-related gene (MSH6), detoxification-related genes (GSTT2, metallothionein), chemoresistant gene ABCG2, and anti-apoptotic gene Bcl-2 (Fig. 6e), and significantly decreased levels of epithelial–mesenchymal transition-associated genes (Slug and Vimentin) (Fig. 6f), as compared to those derived from intact ALDH+ CD44+ CXCR4+ CD24+-cell injection.